
William W. answered 03/22/21
Tutor
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So 160sin2(x)cos2(x) = 160•(1 - cos(2x))/2•(1 + cos(2x))/2 = 40(1 - cos2(2x))
Applying the power reduction formula again:
40(1 - cos2(2x)) = 40(1 - (1 + cos(4x))/2) = 40(2/2 - (1 + cos(4x))/2) = 20(1 - cos(4x)) =
20 - 20cos(4x)